This invention relates to resinous compositions of matter, and more specifically to block copolyestercarbonates having improved weatherability.
Polycarbonates and polyesters, especially poly(alkylene dicarboxylates), and blends thereof are widely employed classes of polymers, in part because of their excellent physical properties including high impact strength. However, their long term color instability is a problem. It causes yellowing, detracting from the transparency and attractiveness of the polymers. Loss of gloss can also be an undesirable long term phenomenon.
Yellowing of polycarbonates and polyesters is caused largely by the action of ultraviolet radiation, which is why such yellowing is frequently designated xe2x80x9cphotoyellowingxe2x80x9d. Numerous means for suppressing photoyellowing have been employed and proposed. Many of these involve incorporation in the polycarbonate of ultraviolet absorbing compounds (UVA""s). For the most part, UVA""s are low molecular weight compounds and they must be employed at relatively low levels, typically up to 1% by weight, to avoid degradation of the physical properties of the polymer such as impact strength and high temperature properties as reflected in heat distortion temperature.
Other polymers have been blended with polycarbonates and/or polyesters to improve their resistance to degradation by ultraviolet radiation and loss of gloss, hereinafter sometimes collectively designated xe2x80x9cweatherabilityxe2x80x9d. Examples of blends of this type are weatherable blends of polycarbonates with copolyesters comprising resorcinol iso/terephthalate units, optionally in combination with xe2x80x9csoft blockxe2x80x9d ester units derived, for example, from an aliphatic or alicyclic dihydroxy compound or dicarboxylic acid. However, such blends are typically immiscible and their use is, therefore, limited to situations in which transparency is not required. In addition, it is of interest to produce a wider variety of weatherable and weatherability-improving polymers.
Japanese Kokai 56/133,332 describes copolyestercarbonates xe2x80x9chaving a highly alternating orientationxe2x80x9d. They are prepared by a 2-step process in which the first step is preparation of a hydroxy-terminated polyester oligomer having a degree of polymerization of 1-2. The second step is treatment of said oligomer with a carbonate precursor such as phosgene to afford a final product having essentially alternating polyester and polycarbonate linkages; i.e., the degree of polymerization of the carbonate blocks is also about 1-2. These copolyestercarbonates are alleged to have excellent heat resistance, solvent resistance and moldability. No details of their weatherability are provided.
The present invention is based on the discovery of a class of block copolyestercarbonates having excellent weatherability. Blends of said copolyestercarbonates with other polymers, specifically polycarbonates and polyesters, are resistant to loss of gloss and have excellent physical properties.
One aspect of the invention, therefore, is block copolyestercarbonates comprising organic carbonate blocks alternating with arylate blocks, said arylate blocks comprising arylate structural units derived from at least one 1,3-dihydroxybenzene moiety and at least one aromatic dicarboxylic acid, and having a degree of polymerization of at least about 4.
Another aspect of the invention is block copolymers comprising moieties of the formula 
wherein each R1 is independently halogen or C1-4 alkyl, each R2 is independently a divalent organic radical, p is 0-3, m is at least about 3 and n is at least about 4.
Another aspect is compositions comprising resinous blends of block copolyestercarbonates as described above with at least one other polymer selected from the group consisting of polycarbonates, poly(alkylene dicarboxylates), polyarylates, polyetherimides, and addition polymers, and any reaction products of said blends.
Still another aspect is a method for preparing block copolyestercarbonates which comprises the steps of:
(A) preparing a hydroxy-terminated polyester intermediate having a degree of polymerization of at least 4 by the reaction of at least one 1,3-dihydroxybenzene moiety with at least one aromatic dicarboxylic acid dichloride under alkaline conditions; and
(B) conducting a reaction of said polyester intermediate with a carbonate precursor.
In one embodiment the present invention comprises block copolyestercarbonates which comprise alternating carbonate and arylate blocks. They include polymers comprising structural units of the formula 
wherein each R1 is independently halogen or C1-12 alkyl, p is 0-3, each R2 is independently a divalent organic radical, m is at least 1 and n is at least about 4. Preferably n is at least about 10, more preferably at least about 20 and most preferably about 30-150. Preferably m is at least about 3, more preferably at least about 10 and most preferably about 20-200. In especially preferred embodiments m is between about 20 and 50. Within the context of the invention xe2x80x9calternating carbonate and arylate blocksxe2x80x9d means that the copolyestercarbonates comprise at least one carbonate block and at least one arylate block.
The arylate blocks contain structural units comprising 1,3-dihydroxybenzene moieties which may be unsubstituted or substituted. Alkyl substituents, if present, are preferably straight-chain or branched alkyl groups, and are most often located in the ortho position to both oxygen atoms although other ring locations are contemplated. Suitable C1-12 alkyl groups include methyl, ethyl, n-propyl, isopropyl, butyl, iso-butyl, t-butyl, nonyl, decyl, and aryl-substituted alkyl, including benzyl, with methyl being particularly preferred. Suitable halogen substituents are bromo, chloro, and fluoro. 1,3-Dihydroxybenzene moieties containing a mixture of alkyl and halogen substituents are also suitable. The value for p may be 0-3, preferably 0-2, and more preferably 0-1. A preferred 1,3-dihydroxybenzene moiety is 2-methylresorcinol. The most preferred 1,3-dihydroxybenzene moiety is unsubstituted resorcinol in which p is zero. Polymers containing mixtures of 1,3-dihydroxybenzene moieties, such as a mixture of unsubstituted resorcinol with 2-methylresorcinol are also contemplated.
In the arylate structural units said 1,3-dihydroxybenzene moieties are bound to aromatic dicarboxylic acid moieties which may be monocyclic moieties, such as isophthalate or terephthalate or their chlorine-substituted derivatives; or polycyclic moieties, such as biphenyl dicarboxylate, diphenylether dicarboxylate, diphenylsulfone dicarboxylate, diphenylketone dicarboxylate, diphenylsulfide dicarboxylate, or naphthalenedicarboxylate, preferably naphthalene-2,6-dicarboxylate; or mixtures of monocyclic and/or polycyclic aromatic dicarboxylates. Preferably, the aromatic dicarboxylic acid moieties are isophthalate and/or terephthalate. Either or both of said moieties may be present. For the most part, both are present in a molar ratio of isophthalate to terephthalate in the range of about 0.25-4.0:1. When the isophthalate to terephthalate ratio is greater than about 4.0:1, then unacceptable levels of cyclic oligomer may form. When the isophthalate to terephthalate ratio is less than about 0.25:1, then unacceptable levels of insoluble polymer may form. Preferably the molar ratio of isophthalate to terephthalate is about 0.4-2.5:1, and more preferably about 0.67-1.5:1.
In the carbonate blocks, each R2 is independently an organic radical derived from a dihydroxy compound. For the most part, at least about 60 percent of the total number of R2 groups in the polymer are aromatic organic radicals and the balance thereof are aliphatic, alicyclic, or aromatic radicals. Suitable R2 radicals include m-phenylene, p-phenylene, 4,4xe2x80x2-biphenylene, 4,4xe2x80x2-bi(3,5-dimethyl)-phenylene, 2,2-bis(4-phenylene)propane and similar radicals such as those which correspond to the dihydroxy-substituted aromatic hydrocarbons disclosed by name or formula (generic or specific) in U.S. Pat. No. 4,217,438, which is incorporated herein by reference.
Presently preferred dihydroxy substituted aromatic reactants are of the general formula: 
wherein Rf is an alkylene, alkylidene, cycloalkylene, cycloalkylidene or arylene linkage or a mixture thereof, a linkage selected from the group consisting of ether, carbonyl, amine, a sulfur or phosphorus containing linkage, Ar and Arxe2x80x2 are arene radicals, Y is a substituent selected from the group consisting of of organic, inorganic and organometallic radicals, X is halogen or a monovalent hydrocarbon group selected from the class consisting of alkyl, aryl and cycloalkyl and conbinations thereof, d represents a whole number of at least 0 up to a maximum equivalent to the number of replaceable hydrogens substituted on the aromatic rings comprising Ar or Arxe2x80x2, e represents a whole number of from 0 to a maximum controlled by the number of replaceable hydrogens on Rf, a, b and c represent whole numbers including 0, when b is not zero, neither a or c may be zero, otherwise either a or c but not both may be 0, when b is zero, the aromatic groups can be joined by direct carbon bonds.
Even more preferred are dihydroxy aromatic reactants of the formulae: 
where independently each R is hydrogen, chlorine, bromine or a C1-30 monovalent hydrocarbon or hydrocarbonoxy group, each Z is hydrogen, chlorine or bromine, subject to the proviso that at least one Z is chlorine or bromine, and 
where independently each R is as defined hereinbefore, and independently Rg and Rh are hydrogen or a C1-30 monovalent hydrocarbon group. Included among suitable dihydroxy-substituted aromatic hydrocarbons are the 2,2,2xe2x80x2,2xe2x80x2-tetrahydro-1,1xe2x80x2-spirobi[1H-indene]diols having formula II: 
wherein each R3 is independently selected from monovalent hydrocarbon radicals and halogen radicals; each R4, R5, R6, and R7 is independently C1-6 alkyl; each R8 and R9 is independently H or C1-6 alkyl; and each n is independently selected from positive integers having a value of from 0 to 3 inclusive. A preferred 2,2,2xe2x80x2,2xe2x80x2-tetrahydro-1,1xe2x80x2-spirobi[1H-indene]-diol is 2,2,2xe2x80x2,2xe2x80x2-tetrahydro-3,3,3xe2x80x2,3xe2x80x2-tetramethyl- 1,1xe2x80x2-spirobi[1H-indene]-6,6xe2x80x2-diol.
More preferably, each R2 is an aromatic organic radical and still more preferably a radical of the formula
xe2x80x94A1xe2x80x94Yxe2x80x94A2xe2x80x94,xe2x80x83xe2x80x83(III)
wherein each A1 and A2 is a monocyclic divalent aryl radical and Y is a bridging radical in which one or two carbon atoms separate A1 and A2. The free valence bonds in formula III are usually in the meta or para positions of A1 and A2 in relation to Y. Compounds in which R2 has formula III are bisphenols, and for the sake of brevity the term xe2x80x9cbisphenolxe2x80x9d is sometimes used herein to designate the dihydroxy-substituted aromatic hydrocarbons; it should be understood, however, that non-bisphenol compounds of this type may also be employed as appropriate.
In formula III A1 and A2 typically represent unsubstituted phenylene or substituted derivatives thereof, illustrative substituents (one or more) being alkyl, alkenyl, and halogen (particularly bromine). Unsubstituted phenylene radicals are preferred. Both A1 and A2 are preferably p-phenylene, although both may be o- or m-phenylene or one o- or m-phenylene and the other p-phenylene.
The bridging radical, Y, is one in which one or two atoms, separate A1 from A2. The preferred embodiment is one in which one atom separates A1 from A2. Illustrative radicals of this type are xe2x80x94Cxe2x95x90O, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94 or xe2x80x94SO2xe2x80x94, methylene, cyclohexylmethylene, 2-[2.2.1]-bicycloheptyl methylene, ethylene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene, cyclododecylidene, and adamantylidene.
Gem-alkylene radicals are often preferred. Also included, however, are unsaturated radicals. For reasons of availability and particular suitability for the purposes of this invention, the preferred bisphenol is 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A or BPA), in which Y is isopropylidene and A1 and A2 are each p-phenylene.
Depending upon whether or not any unreacted 1,3-dihydroxybenzene moiety is present in the reaction mixture as described hereinafter, R2 in the carbonate blocks may consist of or at least partially comprise a radical derived from a 1,3-dihydroxybenzene moiety. Therefore, in one embodiment of the present invention the copolyestercarbonates comprise carbonate blocks with R2 radicals derived from a dihydroxy compound identical to at least one 1,3-dihydroxybenzene moiety in the polyarylate blocks. In another embodiment the copolyestercarbonates comprise carbonate blocks with R2 radicals derived from a dihydroxy compound different from any 1,3-dihydroxybenzene moiety in the polyarylate blocks. In yet another embodiment the copolyestercarbonates comprise carbonate blocks containing a mixture of R2 radicals derived from dihydroxy compounds at least one of which is the same as and at least one of which is different from any 1,3-dihydroxybenzene moiety in the polyarylate blocks. When a mixture of R2 radicals derived from dihydroxy compounds is present, then the molar ratio of dihydroxy compounds identical to those present in the polyarylate blocks to those dihydroxy compounds different from those present in the polyarylate blocks is typically about 1:999 to 999:1. In especially preferred embodiments the copolyestercarbonates comprise carbonate blocks containing a mixture of R2 radicals derived from at least two of unsubstituted resorcinol, a substituted resorcinol, and bisphenol A.
Diblock, triblock, and multiblock copolyestercarbonates are encompassed in the present invention. The chemical linkages between blocks comprising arylate chain members and blocks comprising organic carbonate chain members typically comprise a carbonate linkage between a diphenol residue of an arylate moiety and a "Parenopenst"(Cxe2x95x90O)xe2x80x94Oxe2x80x94 moiety of an organic carbonate moiety, although other types of linkages such as ester and/or anhydride are also possible. A typical carbonate linkage between said blocks is shown in Formula IV, wherein R1 and p are as previously defined: 
In one embodiment the copolyestercarbonate is substantially comprised of a diblock copolymer with a carbonate linkage between an arylate block and an organic carbonate block. In another embodiment the copolyestercarbonate is substantially comprised of a triblock carbonate-ester-carbonate copolymer with carbonate linkages between the arylate block and organic carbonate end-blocks. Copolyestercarbonates with at least one carbonate linkage between an arylate block and an organic carbonate block are typically prepared from 1,3-dihydroxybenzene arylate-containing oligomers containing at least one and preferably two hydroxy-terminal sites (hereinafter sometimes referred to as hydroxy-terminated polyester intermediate).
In another embodiment the copolyestercarbonate comprises arylate blocks linked by carbonate linkages as shown in Formula V: 
wherein R1, p, and n are as previously defined, and the arylate structural units are as described for formula I. Copolyestercarbonates comprising formula V may arise from reaction of hydroxy-terminated polyester intermediate with a carbonate precursor in the substantial absence of any dihydroxy compound different from the hydroxy-terminated polyester intermediate.
In the copolyestercarbonates of the present invention the distribution of the blocks may be such as to provide a copolymer having any desired weight proportion of arylate blocks in relation to carbonate blocks. In general, copolymers containing about 10-99% by weight arylate blocks are preferred.
In step A of the method of this invention for the preparation of block copolyestercarbonates, a polyester intermediate is prepared by combining at least one 1,3-dihydroxybenzene moiety, which may be unsubstituted resorcinol (preferably) or an alkyl- and/or halo-substituted resorcinol or mixtures thereof, with at least one aromatic dicarboxylic acid dihalide, preferably isophthaloyl dichloride, terephthaloyl dichloride or a mixture thereof. The molar ratio of 1,3-dihydroxybenzene moieties to dicarboxylic acid dichlorides is preferably greater than 1:1; e.g., in the range of about 1.01-1.90:1, and more preferably in the range of about 1.01-1.25:1.
The reaction may be performed in the presence of at least one acid acceptor. Suitable acid acceptors include at least one of amines, alkali metal hydroxides, alkaline earth hydroxides, and alkaline earth oxides. Preferred reagents are tertiary amines or alkali metal hydroxides, such as potassium hydroxide or sodium hydroxide. A particularly preferred reagent is sodium hydroxide. The acid acceptor may be included in the reaction mixture in any convenient form, such as solid or liquid, and most preferably as an aqueous solution. An acid acceptor, such as an alkaline reagent, may be present in a molar ratio to dicarboxylic acid dihalides of about 2-2.5:1.
Step A of the method may further comprise combining at least one catalyst with the reaction mixture. Said catalyst may be present at a total level of 0 to 10 mole %, and preferably 0.2 to 6 mole % based on total molar amount of acid chloride groups. Suitable catalysts comprise tertiary amines, quaternary ammonium salts, quaternary phosphonium salts, hexaalkylguanidinium salts, and mixtures thereof.
Suitable tertiary amines include triethylamine, dimethylbutylamine, diisopropylethylamine, 2,2,6,6-tetramethylpiperidine, and mixtures thereof. Other contemplated tertiary amines include N-C1-C6-alkyl-pyrrolidines, such as N-ethylpyrrolidine, N-C1-C6-piperidines, such as N-ethylpiperidine, N-methylpiperidine, and N-isopropylpiperidine, N-C1-C6-morpholines, such as N-ethylmorpholine and N-isopropyl-morpholine, N-C1-C6-dihydroindoles, N-C1-C6-dihydroisoindoles, N-C1-C6-tetrahydroquinolines, N-C1-C6-tetrahydroisoquinolines, N-C1-C6-benzomorpholines, 1-azabicyclo-[3.3.0]-octane, quinuclidine, N-C1-C6-alkyl-2-azabicyclo-[2.2.1]-octanes, N-C1-C6-alkyl-2-azabicyclo-[3.3.1]-nonanes, and N-C1-C6-alkyl-3-azabicyclo-[3.3.1]-nonanes, N,N,Nxe2x80x2,Nxe2x80x2-tetraalkylalkylene-diamines, including N,N,Nxe2x80x2,Nxe2x80x2-tetraethyl-1,6-hexanediamine. Particularly preferred tertiary amines are triethylamine and N-ethylpiperidine.
When the catalyst comprises at least one tertiary amine, then said catalyst may be present at a total level of 0.1 to 10 mole %, preferably 0.2 to 6 mole %, and more preferably 0.5 to 2 mole %, based on total molar amount of acid chloride groups. In one embodiment of the invention all of the at least one tertiary amine is present at the beginning of the reaction before addition of dicarboxylic acid dichloride to 1,3-dihydroxybenzene moiety. In another embodiment a portion of any tertiary amine is present at the beginning of the reaction and a portion is added following or during addition of dicarboxylic acid dichloride to 1,3-dihydroxybenzene moiety. In this latter embodiment the amount of any tertiary amine initially present with 1,3-dihydroxybenzene moiety may range from about 0.005 wt. % to about 10 wt. %, preferably from about 0.01 to about 1 wt. %, and more preferably from about 0.02 to about 0.3 wt. % based on total amine catalyst.
Suitable quaternary ammonium salts, quaternary phosphonium salts, and hexaalkylguanidinium salts include halide salts such as tetraethylammonium bromide, tetraethylammonium chloride, tetrapropylammonium bromide, tetrapropylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, methyltributylammonium chloride, benzyltributylammonium chloride, benzyltriethylammonium chloride, benzyltrimethylammonium chloride, trioctylmethylammonium chloride, cetyldimethylbenzylammonium chloride, octyltriethylammonium bromide, decyltriethylammonium bromide, lauryltriethylammonium bromide, cetyltrimethylammonium bromide, cetyltriethylammonium bromide, N-laurylpyridinium chloride, N-laurylpyridinium bromide, N-heptylpyridiniuni bromide, tricaprylylmethylammonium chloride (sometimes known as ALIQUAT 336), methyltri-C8-C10-alkyl-ammonium chloride (sometimes known as ADOGEN 464), N,N,Nxe2x80x2,Nxe2x80x2,Nxe2x80x2-pentaalkyl-alpha, omega-amineammonium salts such as disclosed in U.S. Pat. No. 5,821,322; tetrabutylphosphonium bromide, benzyltriphenylphosphonium chloride, triethyloctadecylphosphonium bromide, tetraphenylphosphonium bromide, triphenylmethylphosphonium bromide, trioctylethylphosphonium bromide, cetyltriethylphosphonium bromide, hexaalkylguanidinium halides, hexaethylguanidinium chloride, and the like, and mixtures thereof.
An organic solvent, typically a water-immiscible solvent, is also generally present. Suitable water-immiscible solvents include dichloromethane, trichloroethylene, tetrachloroethane, chloroform, 1,2-dichloroethane, toluene, xylene, trimethylbenzene, chlorobenzene, o-dichlorobenzene, and mixtures thereof. Particularly preferred water-immiscible solvents are chlorinated aliphatic compounds such as dichloromethane. Thus, the reaction is generally conducted in a 2-phase system.
If desired, the reaction mixture may further comprise a reducing agent. Suitable reducing agents include, for example, sodium sulfite, sodium hydrosulfite, or a borohydride, such as sodium borohydride. When present, any reducing agents are typically used in quantities of from 0.25 to 2 mole %, based on moles of 1,3-dihydroxybenzene moiety. The reaction mixture may also comprise a metal chelating agent such as sodium gluconate.
The temperature of the reaction mixture may be from about 0xc2x0 C. to the boiling point the solvent or mixture of solvents present. In an interfacial process which employs both water and an organic solvent essentially immiscible with water, the temperature typically ranges from ambient temperature to the boiling point of the water-organic solvent mixture under the reaction conditions. In a preferred embodiment the reaction is performed at the boiling point of the organic solvent in the water-organic solvent mixture. In an especially preferred embodiment the reaction is performed at the boiling point of dichloromethane.
Following the completion of polyester intermediate preparation, it is sometimes advantageous to acidify the aqueous phase of the two-phase system prior to phase separation. The organic phase, which contains the polyester intermediate, may then be subjected to step B which is the block copolyestercarbonate-forming reaction. Alternatively, the polyester intermediate may be recovered from solution for subsequent use in a copolymer formation step. It is also contemplated, however, to proceed to step B without acidification or separation, and this is often possible without loss of yield or purity.
Polyester intermediates from step A typically have weight average molecular weight (vs. polystyrene standards) of at least about 900, preferably at least about 2400, and more preferably at least about 4800. In especially preferred embodiments said oligomers have weight average molecular weights of about 10,000 to about 40,000, and more preferably about 15,000 to about 32,000. Said intermediates typically have about 300-1500 ppm carboxylic acid end-groups and about 2-37,000 ppm, and preferably about 2400-9700 ppm phenolic hydroxy end-groups. Carboxylic acid end-groups may be present through hydrolysis of acid chloride groups under the reaction conditions and as adventitious acid groups present in dicarboxylic acid dichloride starting material.
It is also within the scope of the invention to prepare the polyester intermediate in the absence of water entirely in an organic liquid, with the use of an acid acceptor soluble in said liquid. Suitable acid acceptors for such use include tertiary amines such as triethylamine. It is also within the scope of the invention to prepare the polyester intermediate in a substantially solvent-free process, for example a melt process or a solid-state polymerization process. It is also contemplated to conduct the first step by other ester-forming methods, as illustrated by transesterification using aromatic diesters and a 1,3-dihydroxybenzene either in a solvent or in the melt.
In step B of the method the carbonate precursor is preferably phosgene. When phosgene is employed, this step may be conducted according to art-recognized interfacial procedures (i.e., also in a two-phase system) employing a suitable interfacial polymerization catalyst and an alkaline reagent, preferably sodium hydroxide. Optionally a branching agent and/or a chain termination agent such as described below may be present. To suppress scrambling of the block copolymer, the pH is maintained at a relatively low level, typically in the range of about 4-9, for the initial part of the phosgenation reaction; it may be increased to about 10-13 during the latter part of said reaction.
Step B is preferably conducted in the presence of at least one organic dihydroxy compound different from hydroxy-terminated polyester intermediate. Said organic dihydroxy compound typically has the formula HOxe2x80x94R2xe2x80x94OH, wherein R2 is as previously defined. Therefore, in one embodiment the method of the present invention comprises conducting the reaction of step B in the presence of at least one organic dihydroxy compound of the formula HOxe2x80x94R2xe2x80x94OH identical to at least one 1,3-dihydroxybenzene moiety in the polyarylate blocks prepared in step A. In another embodiment the method comprises conducting the reaction of step B in the presence of at least one organic dihydroxy compound of the formula HOxe2x80x94R2xe2x80x94OH different from any 1,3-dihydroxybenzene moiety in the polyarylate blocks prepared in step A. In a preferred embodiment the method comprises conducting the reaction of step B in the presence of a mixture of organic dihydroxy compounds of the formula HOxe2x80x94R2xe2x80x94OH at least one of which is the same as and at least one of which is different from any 1,3-dihydroxybenzene moiety in the polyarylate blocks. In a more preferred embodiment the method comprises conducting the reaction of step B in the presence of a mixture of two organic dihydroxy compounds of the formula HOxe2x80x94R2xe2x80x94OH one of which is the same as and one of which is different from any 1,3-dihydroxybenzene moiety in the polyarylate blocks. When a mixture of dihydroxy compounds is present, then the molar ratio of dihydroxy compounds identical to those present in the polyarylate blocks to those dihydroxy compounds different from those present in the polyarylate blocks is typically about 1:999 to 999:1. In especially preferred embodiments the method comprises conducting the reaction of step B in the presence of a mixture of dihydroxy compounds comprising at least two of unsubstituted resorcinol, a substituted resorcinol, and bisphenol A.
The at least one organic dihydroxy compound different from hydroxy-terminated polyester intermediate may be introduced into the reaction mixture of step B through any convenient method of combination. In one embodiment said at least one organic dihydroxy compound may be present as unreacted 1,3-dihydroxybenzene moiety from step A. In another embodiment said at least one organic dihydroxy compound may be added following step A, before or during reaction with carbonate precursor in step B. In a preferred embodiment at least one organic dihydroxy compound is present as unreacted 1,3-dihydroxybenzene moiety from step A and at least one organic dihydroxy compound may be added following step A, before or during reaction with carbonate precursor in step B. Any dihydroxy compound added following step A, before or during reaction with carbonate precursor in step B, may be the same as or different from any 1,3-dihydroxybenzene moiety present initially in step A. In a particularly preferred embodiment said at least one organic dihydroxy compound comprises at least one unsubstituted resorcinol or substituted resorcinol from step A and at least one dihydroxy compound added following step A different from unsubstituted resorcinol or substituted resorcinol. In an especially preferred embodiment a molar excess of resorcinol (relative to total moles acid chloride species present) is employed in step A, in which case there may be some unreacted resorcinol remaining, and bisphenol A is added before or during reaction with carbonate precursor in step B. The amount of any 1,3-dihydroxybenzene moiety remaining unreacted from step A is less than about 15 mole %, preferably less than about 10 mole %, and more preferably less than about 5 mole % of the 1,3-dihydroxybenzene moiety initially present in step A. In an especially preferred embodiment the amount of 1,3-dihydroxybenzene moiety remaining unreacted from step A is less than about 2 mole % of the 1,3-dihydroxybenzene moiety initially present in step A.
At least one chain-stopper (also referred to sometimes hereinafter as capping agent) may also be present in either or both of steps A and B, and said chain-stopper may be incorporated into the structures of copolyestercarbonates of the invention. When any chain-stopper is employed in step A, the amount is such that a substantial portion of polyester intermediate end-groups remain as hydroxy groups for use in copolymer formation in step B through reaction with carbonate precursor. If a chain-stopper is employed in both of steps A and B, then said chain stoppers may be the same or different. One purpose of adding at least one chain-stopper is to limit the molecular weight of polymer comprising arylate polyester chain members, thus providing polymer with controlled molecular weight and favorable processability. A chain-stopper may be at least one of mono-phenolic compounds, mono-carboxylic acid chlorides, and/or mono-chloroformates. Typically, the at least one chain-stopper may be present in quantities of 0.05 to 10 mole %, based on total dihydroxy compounds in the case of mono-phenolic compounds when used in either step A and/or step B, and based on total acid dichlorides in the case mono-carboxylic acid chlorides and/or mono-chloroformates when used in step A.
Suitable mono-phenolic compounds as chain-stoppers include monocyclic phenols, such as phenol, C1-C22 alkyl-substituted phenols, p-cumyl-phenol, p-tertiary-butyl phenol, hydroxy diphenyl; monoethers of diphenols, such as p-methoxyphenol. Alkyl-substituted phenols include those with branched chain alkyl substituents having 8 to 9 carbon atoms, preferably in which about 47 to 89% of the hydrogen atoms are part of methyl groups as described in U.S. Pat. No. 4,334,053. For some embodiments the use of a mono-phenolic UV screener as capping agent is preferred. Such compounds include 4-substituted-2-hydroxybenzophenones and their derivatives, aryl salicylates, monoesters of diphenols, such as resorcinol monobenzoate, 2-(2-hydroxyaryl)-benzotriazoles and their derivatives, 2-(2-hydroxyaryl)-1,3,5-triazines and their derivatives, and like compounds. Especially preferred mono-phenolic chain-stoppers are phenol, p-cumylphenol, and resorcinol monobenzoate.
Suitable mono-carboxylic acid chlorides as chain-stoppers include monocyclic, mono-carboxylic acid chlorides, such as benzoyl chloride, C1-C22 alkyl-substituted benzoyl chloride, toluoyl chloride, halogen-substituted benzoyl chloride, bromobenzoyl chloride, cinnamoyl chloride, 4-nadimidobenzoyl chloride, and mixtures thereof; polycyclic, mono-carboxylic acid chlorides, such as trimellitic anhydride chloride, and naphthoyl chloride; and mixtures of monocyclic and polycyclic mono-carboxylic acid chlorides. The chlorides of aliphatic monocarboxylic acids with up to 22 carbon atoms are also suitable. Functionalized chlorides of aliphatic monocarboxylic acids, such as acryloyl chloride and methacryloyl chloride, are also suitable. Suitable mono-chloroformates include monocyclic, mono-chloroformates, such as phenyl chloroformate, alkyl-substituted phenyl chloroformate, p-cumyl phenyl chloroformate, toluene chloroformate, and mixtures thereof.
A chain-stopper can be combined together with the 1,3-dihydroxybenzene moieties, can be contained in the solution of dicarboxylic acid dichlorides, or can be added to the reaction mixture after production of a precondensate. If mono-carboxylic acid chlorides and/or mono-chloroformates are used as chain-stoppers, they are preferably introduced together with dicarboxylic acid dichlorides. These chain-stoppers can also be added to the reaction mixture at a moment when the chlorides of dicarboxylic acid have already reacted substantially or to completion. If phenolic compounds are used as chain-stoppers, they can be added to the reaction mixture during the reaction in step A and/or step B.
In another embodiment the method of the invention may encompass the inclusion of at least one branching agent in step A and/or step B. Said branching agent may be incorporated into the structures of the copolyestercarbonates of the invention. Suitable branching agents include trifunctional or higher functional carboxylic acid chloride and/or trifunctional or higher functional phenol. Such branching agents, if included, can preferably be used in quantities of 0.005 to 1 mole %, based on dicarboxylic acid dichlorides or on total dihydroxy compound present, respectively. Illustrative examples of suitable branching agents include trifunctional or higher carboxylic acid chlorides, such as trimesic acid trichloride, cyanuric acid trichloride, 3,3xe2x80x2,4,4xe2x80x2-benzophenone tetracarboxylic acid tetrachloride, 1,4,5,8-naphthalene tetracarboxylic acid tetrachloride or pyromellitic acid tetrachloride, and trifunctional or higher phenols, such as phloroglucinol, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-2-heptene, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane, 1,3,5-tri-(4-hydroxyphenyl)-benzene, 1,1,1-tri-(4-hydroxyphenyl)-ethane, tri-(4-hydroxyphenyl)-phenyl methane, 2,2-bis-[4,4-bis-(4-hydroxyphenyl)-cyclohexyl]-propane, 2,4-bis-(4-hydroxyphenylisopropyl)-phenol, tetra-(4-hydroxyphenyl)-methane, 2,6-bis-(2-hydroxy-5-methylbenzyl)-4-methyl phenol, 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)-propane, tetra-(4-[4-hydroxyphenylisopropyl]-phenoxy)-methane, 1,4-bis-[(4,4-dihydroxytri-phenyl)methyl]-benzene.
Following completion of both reactions, the block copolyestercarbonate may be used in solution or transferred by any convenient procedure to some other solvent for use. For most applications the copolyestercarbonate is recovered and isolated from solution by conventional procedures. These may include, for example, at least one step of anti-solvent precipitation, washing, drying and devolatilization-pelletization via extrusion.
Block copolyestercarbonates made by the method of the present invention typically have less than about 100 ppm, preferably less than about 50 ppm, and more preferably less than about 20 ppm phenolic end-groups. Said copolymers typically contain less than about 50 ppm and preferably less than about 25 ppm free 1,3-dihydroxybenzene moiety. The copolymers typically have less than about 200 ppm, preferably less than about 100 ppm, and more preferably less than about 50 ppm carboxylic acid end-groups. The concentration of carboxylic acid end-groups in the copolyestercarbonates is typically less than that present in the polyester intermediate from step A. Carboxylic acid end-groups in said polyester intermediate may react with carbonate precursor in step B. For example, when phosgene is the carbonate precursor, carboxylic acid groups may react to form carboxylic acid chlorides which may then react with any phenolic groups present, for example phenolic end-groups on polyester intermediate and any free 1,3-dihydroxybenzene moiety added in step A.
In one of its embodiments. the present invention comprises the copolyestercarbonates as described. In the methods of making said copolyestercarbonates there may be present following step B some polyester intermediate from step A which is not covalently bound to a carbonate moiety. For example there may be present a polyester intermediate possessing end-groups which are not reactive with carbonate precursor. Illustrative examples of such end-groups may include carboxylic acid or carboxylic acid chloride or end-capped species without any functional group. Therefore, in another of its embodiments the present invention comprises the said copolyestercarbonates in combination with polyarylate homopolymer containing structural units comprising those of the polyarylate blocks in the copolyestercarbonate, said polyarylate homopolymer being made in step A of the same process as said copolyestercarbonate without isolation of said copolyestercarbonate. When it is desired to isolate substantially pure copolyestercarbonate, then the level of said polyarylate homopolymer present in copolyestercarbonate is preferably less than about 20 wt. %, more preferably less than about 10 wt. % and most preferably less than about 4 wt. % of copolyestercarbonate. In especially preferred embodiments the level of said polyarylate homopolymer is less than about 1 wt. % of copolyestercarbonate isolated substantially pure. When it is desired to prepare a blend of copolyestercarbonate with polyarylate homopolymer through synthesis in steps A and B, then proportions of the copolyestercarbonates in such blends are typically up to about 80 wt. % of the composition.
When an organic dihydroxy compound different from the 1,3-dihydroxybenzene moiety of step A is present in step B, then said dihydroxy compound may undergo transesterification with arylate blocks in both copolyestercarbonate and in any polyarylate homopolymer present, depending upon reaction parameters such as pH and temperature. Therefore, in another of its embodiments the present invention comprises the said copolyestercarbonates in combination with polyarylate copolymer with structural units comprising 1,3-dihydroxybenzene moieties from step A and organic dihydroxy compound added for step B, both in combination with aromatic dicarboxylic acid moieties as described, said polyarylate copolymer being derived from the synthesis process. The level of said polyarylate copolymer present in copolyestercarbonate is preferably less than about 20 wt. %, more preferably less than about 5 wt. % and most preferably less than about 2 wt. % of copolyestercarbonate. In especially preferred embodiments the level of said polyarylate copolymer is less than about 1 wt. % of copolyestercarbonate.
In yet another of its embodiments the present invention comprises copolyestercarbonates in which a portion of the arylate blocks have undergone transesterification with and incorporation of organic dihydroxy compound added in step B as described above. For example, in a typical embodiment copolyestercarbonates may be produced in which an organic dihydroxy compound such as bisphenol A is incorporated into a portion of the arylate blocks, either before, during, or after carbonate block formation with hydroxy-terminated polyester intermediate. The level of said organic dihydroxy compound added in step B incorporated into said arylate blocks is preferably less than about 20 wt. %, more preferably less than about 5 wt. % and most preferably less than about 2 wt. % of copolyestercarbonate. In especially preferred embodiments the level of incorporation of said organic dihydroxy compound added in step B into said arylate blocks is less than about 1 wt. % of copolyestercarbonate.
When step B is performed in the presence of at least one organic dihydroxy compound different from hydroxy-terminated polyester intermediate produced in step A, then polycarbonate homopolymer may be formed which is not covalently bound to polyester intermediate. Therefore, in another of its embodiments the present invention comprises the said copolyestercarbonates in combination with polycarbonate homopolymer containing structural units comprising those of the polycarbonate blocks in the copolyestercarbonate, said polycarbonate homopolymer being made in step B of the same process as said copolyestercarbonate without isolation of said copolyestercarbonate. When it is desired to isolate substantially pure copolyestercarbonate, then the level of said polycarbonate homopolymer present in copolyestercarbonate is preferably less than about 20 wt. %, more preferably less than about 10 wt. % and most preferably less than about 4 wt. % of copolyestercarbonate. In especially preferred embodiments the level of said polycarbonate homopolymer is less than about 2 wt. % of copolyestercarbonate isolated substantially pure. When it is desired to prepare a blend of copolyestercarbonate with at least one polycarbonate homopolymer through synthesis in steps A and B, then the at least one polycarbonate homopolymer in the blends may be prepared essentially simultaneously with carbonate block formation in the copolyestercarbonate in step B. Alternatively, said at least one polycarbonate homopolymer in the blends may be prepared after the block copolyestercarbonate formation is at least partially or essentially complete, for example, in one option, through addition of more organic dihydroxy compound, carbonate precursor, and chain stopper. The proportions of the copolyestercarbonates in such blends are determined chiefly by the resulting proportions of arylate blocks, which comprise the active weatherability-improving entities, typical proportions providing about 10-50% by weight of arylate blocks in the blend. Typically blends of copolyestercarbonate with up to about 95 wt. % polycarbonate homopolymer may be prepared through synthesis in steps A and B. In a particular embodiment blends of copolyestercarbonate comprising bisphenol A carbonate blocks may be prepared along with bisphenol A polycarbonate homopolymer through synthesis in step A and step B in the presence of phosgene.
In addition when step B is performed in the presence of at least one organic dihydroxy compound different from hydroxy-terminated polyester intermediate produced in step A, then a new polyarylate homopolymer may be formed through reaction, for example, of said organic dihydroxy compound with any aromatic dicarboxylic acid dihalide present in the reaction mixture. For example, aromatic dicarboxylic acids may be present in the reaction mixture of step A, either through hydrolysis of aromatic dicarboxylic acid dihalide or as impurities initially present in aromatic dicarboxylic acid dihalide. Said aromatic dicarboxylic acids may be converted to the corresponding dicarboxylic acid dichlorides through reaction with phosgene in step B. Therefore, in another of its embodiments the present invention comprises the said copolyestercarbonates in combination with polyarylate homopolymer containing structural units comprising organic dihydroxy compound added in step B in combination with aromatic dicarboxylic acid moieties as described, said polyarylate homopolymer being made in the same process as said copolyestercarbonate without isolation of said copolyestercarbonate. The level of said polyarylate homopolymer present in copolyestercarbonate is preferably less than about 12 wt. %, more preferably less than about 6 wt. % and most preferably less than about 4 wt. % of copolyestercarbonate. In especially preferred embodiments the level of said polyarylate homopolymer is less than about 2 wt. % of copolyestercarbonate. In an illustrative example bisphenol A polyarylate from reaction of terephthaloyl chloride and/or isophthaloyl chloride with bisphenol A added in step B may be present in the copolyestercarbonates of the invention.
The block copolyestercarbonates of this invention are polymers having excellent physical properties. Their light transmitting properties are similar to those of polycarbonates. Thus, they are substantially transparent and may be employed as substitutes for polycarbonates in the fabrication of transparent sheet material when improved weatherability is mandated.
It is believed that the weatherability and certain other beneficial properties of the copolyestercarbonates of the invention are attributable, at least in part, to the occurrence of thermally or photochemically induced Fries rearrangement of arylate blocks to yield o-hydroxybenzophenone moieties or analogs thereof which serve as stabilizers to UV radiation. More particularly, at least a portion of arylate polyester chain members can rearrange to yield chain members with at least one hydroxy group ortho to at least one ketone group. Such rearranged chain members are typically o-hydroxybenzophenone-type chain members comprising one or more of the following structural moieties: 
wherein R1 and p are as previously defined. Thus, in one of its embodiments the present invention comprises compositions containing copolyestercarbonates containing structural units comprising those shown in Formula IX wherein R1, R2, p, m, and n are as previously defined: 
It is also contemplated to introduce moieties of the types illustrated in Formulas VI, VII, and VIII via synthesis and polymerization of appropriate monomers in copolyestercarbonates. In one embodiment the present invention provides copolyestercarbonates comprising structural units represented by Formulas X and XI, 
wherein R1 and p are as previously defined and wherein the molar ratio of structural units represented by Formula X to structural units represented by Formula XI ranges from about 99:1 to about 1:1, and preferably from about 99:1 to about 80:20. Although iso- and terephthalate units are illustrated in Formulas X and XI, the dicarboxylic acid residues in the arylate blocks may be derived from any suitable dicarboxylic acid residue, as defined hereinabove, or mixture of suitable dicarboxylic acid residues. In preferred embodiments p in both Formulas X and XI is zero and the arylate blocks comprise dicarboxylic acid residues derived from a mixture of iso- and terephthalic acid residues, wherein the molar ratio of isophthalate to terephthalate is about 0.25-4.0:1, preferably about 0.4-2.5:1, and more preferably about 0.67-1.5:1.
The block copolyestercarbonates may also be employed as weatherability-improving additives for other polymers, especially polycarbonates, polyesters, polyarylates, polyetherimides and addition polymers. The polycarbonates in the blend compositions of the invention are, for the most part, similar in molecular structure to the carbonate blocks of the block copolyestercarbonate as described hereinabove, with bisphenol A homo- and copolycarbonates generally being preferred. Polyesters are illustrated by poly(alkylene dicarboxylates), especially poly(ethylene terephthalate) (hereinafter sometimes designated xe2x80x9cPETxe2x80x9d), poly(1,4-butylene terephthalate) (hereinafter sometimes designated xe2x80x9cPBTxe2x80x9d), poly(trimethylene terephthalate) (hereinafter sometimes designated xe2x80x9cPTTxe2x80x9d), poly(ethylene naphthalate) (hereinafter sometimes designated xe2x80x9cPENxe2x80x9d), poly(1,4-butylene naphthalate) (hereinafter sometimes designated xe2x80x9cPBNxe2x80x9d), poly(cyclohexanedimethanol terephthalate) (hereinafter sometimes designated xe2x80x9cPCTxe2x80x9d), poly(cyclohexanedimethanol-co-ethylene terephthalate) (hereinafter sometimes designated xe2x80x9cPETGxe2x80x9d), and poly(1,4-cyclohexanedimethyl-1,4-cyclohexanedicarboxylate) (hereinafter sometimes designated xe2x80x9cPCCDxe2x80x9d), and especially poly(alkylene arenedioates), with poly(ethylene terephthalate) and poly(1,4-butylene terephthalate) being preferred. Polyarylates include those with structural units comprising the 1,3-dihydroxybenzene moiety present in the arylate blocks of the copolyestercarbonates, those with structural units comprising any organic dihydroxy compound added in the carbonate block formation step in synthesis of said copolyestercarbonates, and those with structural units comprising both of the aforementioned dihydroxy moieties. Illustrative examples include polyarylates comprising terephthalate and/or isophthalate structural units in combination with one or more of unsubstituted resorcinol, substituted resorcinol, and bisphenol A. The polyetherimide resins useful with the present invention are generically known compounds whose preparation and properties are described in U.S. Pat. Nos. 3,803,085 and 3,905,942, each of which is incorporated herein by reference.
Suitable addition polymers include homopolymers and copolymers, especially homopolymers of alkenylaromatic compounds, such as polystyrene, including syndiotactic polystyrene, and copolymers of alkenylaromatic compounds with ethylenically unsaturated nitrites, such as acrylonitrile and methacrylonitrile; dienes, such as butadiene and isoprene; and/or acrylic monomers, such as ethyl acrylate. These latter copolymers include the ABS (acrylonitrile-butadiene-styrene) and ASA (acrylonitrile-styrene-alkyl acrylate) copolymers. Suitable addition polymers also include acrylic polymers such as those of (meth)acrylamides or of alkyl (meth)acrylates such as poly(methyl methacrylate) (xe2x80x9cPMMAxe2x80x9d), wherein the nomenclature xe2x80x9cmeth(acryl . . . )xe2x80x9d indicates that both acryl and methacryl polymers are designated.
Proportions of the block copolyestercarbonates in such blends are determined chiefly by the resulting proportions of arylate blocks, which comprise the active weatherability-improving entities, typical proportions providing about 10-50% by weight of arylate blocks in the blend. By reason of some degree of incompatibility between the block copolyestercarbonates of the invention and the various polymers in which they may be incorporated, said blends are often not transparent. However, transparent blends may often be prepared by adjusting the length of the arylate blocks in the block copolyestercarbonates. The other properties of said blends are excellent.
The blend compositions of the invention may be prepared by such conventional operations as solvent blending or melt blending as by an extrusion process. They may additionally contain art-recognized additives including impact modifiers, UV screeners, flame retardants, stabilizers, ester interchange inhibitors, flow aids and mold release agents. The blends may contain fillers such as glass fibers, glass fiber fabric, chopped glass, knit glass fiber fabric, glass spheres, KEVLAR fiber, polyphenylene sulfide fiber, woven basalt fiber fabric, silicates, zeolites, titanium dioxide, stone powder, carbon fibers, carbon black, graphite, calcium carbonate, talc, mica, lithopone, zinc oxide, zirconium silicate, iron oxides, diatomaceous earth, calcium carbonate, magnesium oxide, chromic oxide, zirconium oxide, aluminum oxide, crushed quartz, talc, clay, kaolin, asbestos, cellulose, wood flour, cork, cotton and synthetic textile fibers, especially reinforcing fillers such as glass fibers and carbon fibers, as well as colorants such as metal flakes, glass flakes and beads, ceramic particles, other polymer particles, dyes and pigments which may be organic, inorganic or organometallic. In addition It is intended that the blend compositions include simple physical blends and any reaction products thereof, as illustrated by polyester-polycarbonate transesterification products.
The block copolyestercarbonates of the invention, and blends thereof, may be used in various applications, especially those involving outdoor use and storage and hence requiring resistance to weathering. These applications include automotive, truck, agricultural vehicle, military vehicle, and motorcycle exterior and interior components, including panels, quarter panels, rocker panels, trim, fenders, doors, decklids, trunklids, hoods, bonnets, roofs, bumpers, fascia, grilles, mirror housings, pillar appliques, cladding, body side moldings, wheel covers, hubcaps, door handles, spoilers, window frames, headlamp bezels, headlamps, tail lamps, tail lamp housings, tail lamp bezels, license plate enclosures, roof racks, and running boards; enclosures, housings, panels, and parts for outdoor vehicles and devices; enclosures for electrical and telecommunication devices; outdoor furniture; aircraft components; boats and marine equipment, including trim, enclosures, and housings; outboard motor housings; depth finder housings, personal water-craft; jet-skis; pools; spas; hot-tubs; steps; step coverings; building and construction applications such as glazing, roofs, windows, floors, decorative window furnishings or treatments; treated glass covers for pictures, paintings, posters, and like display items; wall panels, and doors; protected graphics; outdoor and indoor signs; enclosures, housings, panels, and parts for automatic teller machines (ATM); enclosures, housings, panels, and parts for lawn and garden tractors, lawn mowers, and tools, including lawn and garden tools; window and door trim; sports equipment and toys; enclosures, housings, panels, and parts for snowmobiles; recreational vehicle panels and components; playground equipment; articles made from plastic-wood combinations; golf course markers; utility pit covers; computer housings; desk-top computer housings; portable computer housings; lap-top computer housings; palm-held computer housings; monitor housings; printer housings; keyboards; FAX machine housings; copier housings; telephone housings; mobile phone housings; radio sender housings; radio receiver housings; light fixtures; lighting appliances; network interface device housings; transformer housings; air conditioner housings; cladding or seating for public transportation; cladding or seating for trains, subways, or buses; meter housings; antenna housings; cladding for satellite dishes; coated helmets and personal protective equipment; coated synthetic or natural textiles; coated photographic film and photographic prints; coated painted articles; coated dyed articles; coated fluorescent articles; coated foam articles; and like applications. The invention further contemplates additional fabrication operations on said articles, such as, but not limited to, molding, in-mold decoration, baking in a paint oven, lamination, and/or thermoforming.